Net Long-Term Migration to U.K. Rose 43% in 12 Months to June 2014, According to Data Released Thursday

LONDON—Prime Minister David Cameron on Friday will say he wants to introduce tough restrictions on the welfare benefits that European Union nationals can receive in Britain to reduce growing immigration from the continent, a move that may please euroskeptics at home but irk some of his European counterparts.

And in a veiled threat to the rest of Europe that his support for Britain’s membership in the EU has its limits, Mr. Cameron plans to say that if his demands fall on deaf ears, “then of course I rule nothing out,” according...